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Edible Vaccines
Edible Vaccines A vaccine is a substance that when introduced into an organism will induce an immune response that will provide an immunity to the disease the vaccine is specific for. To make a vaccine, an antigen, from the disease in question is extracted and introduced into a host. Antigens are proteins attached to viruses that are recognized by immune systems. Although they indicate the presence of the virus, antigens themselves are not harmful. Due to this, it is possible to introduce viral antigens into hosts without causing the disease. By introducing the antigens into the host, the hosts' immune system learns to recognize the foreign proteins and destroy them. Through immune system memory, hosts are able to retain the ability to recognize these antigens and protect against them. The production and maintenance of vaccines is extremely cumbersome however. Vaccines need to remain cool, syringes are needed to introduce them to hosts and sometimes more than one injection is needed. A new solution to this problem is edible vaccines. These are genetically modified, edible plants that contain the antigens used in vaccine production.2 The Process Making edible vaccines involves the synthesis of the proteins in vaccines by plants. First the antigen gene in the viruses' DNA is isolated. Next, one of a variety of different methods to introduce the DNA into the plants genome through transformation is employed. The Agrobacterium Mediated Gene Transfer Method involves inserting the viral DNA into the T-region of a disarmed Ti plasmid of Agrebacterium. Next, this recombinant DNA is put into Agrebacterium, a plant pathogen and cultured with plant tissues that will be transformed. The Biolistic Method involves coating the DNA in question with metal and firing the particles into plant cells using a gene gun. The plant cells that take up the DNA are allowed to grow then are cloned to produce many identical plants containing the DNA encoded antigen.2 Edible Hepatits B Vaccine The vaccine for Hepatits B is constructed from the surface antigen HBsAg. This antigen was cloned into a CaMv plasmid and then regenerated from transformed plant cells that were shown to produce HbsAg. This antigen was generated in transgenic potatoes, but they did not produce enough of the antigen to make a real difference. More success was found with making transformed tobacco plants containing the HBsAg antigen coupled with the use of untranslated regions (UTRs) from soybean (vspB) and potato (pinII) 3' - UTRs. The introduction of these UTRs significantly increased the amount of HBsAg expressed in the tobacco plant. Tests showed that ingestion of the transgenic tobacco by animals showed an increased serum antibody production. This would be the usual reaction to the immune systems recognition of the HBsAg antigen.2 The Original Idea The idea for edible vaccines stemmed in the 1990's from Charles J. Arntzen, an American scientist. He was aware of the problems with getting vaccines to third world countries and appalled by the death rates of children who could have been saved with simple vaccination. His solution to this problem was to genetically modify fruits and vegetables, capable of growing in these remote places, that contained vaccine properties. Although there has been some success incorporating the DNA needed for vaccines into these plants, the resources needed to perfect the edible vaccines and produce them on a larger scale are very expensive and the funding simply did not exist.1 References 1 Langridge, W. H. R. (2000). Edible Vaccines Scientific American(71). https://www.mcdb.ucla.edu/Research/Goldberg/HC70A_W12/pdf/EdibleVaccines.pdf 2 Neerah Mishra, P. N. G., Kalip Khatri, Amit K Goyal and Suresh P Vyas. (2008). Edible vaccines: A new appraoch to oral immunization Indian Journal of Biotechnology 7, 283-294. http://nopr.niscair.res.in/bitstream/123456789/1841/1/IJBT%207(3)%20283-294.pdf